There was a variety memory that used iron ferrite / ceramic rings. These were arranged on a wire grid. The rings were located at the intersections of the wires, and the wires passed through the loops in the rings.

I don't know if this was used in the 360, but the vintage is right.

Ah, here we go:

http://www.google.com/search?q=ferrite+core+memory&hl=en&safe=off&client=firefox-a&hs=UJf&rls=org.mozilla:en-US:official&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=bGAcTtLuOsXZgQfO3uDJCQ&ved=0CDIQsAQ&biw=1077&bih=911